There is significant interest in alternative fuels which are non-petroleum based for many reasons, including environmental, economic, political, and other reasons. Biodiesel fuel is one alternative based upon renewable resources. Biodiesel is a mono-alkyl ester of long chain fatty acids, such as methyl ester derived from fats and oils, and provides lower emissions as compared to petroleum-based diesel fuel. The cetane number, energy content, viscosity, and phase changes of biodiesel are similar to petroleum diesel.
Biodiesel is derived from a transesterification chemical process wherein the triglyceride feedstock, such as fat or vegetable oil, is processed for conversion into methyl esters (biodiesel) and glycerin.
The American Society for Testing Materials (ASTM) has developed standards for biodiesel fuels, with the most common being D-6751. ASTM standard D-6751 sets commercial quality specifications required for biodiesel fuel. The D-6751 standard requires water and sediment be less than 0.050%, by volume, as measured by ASTM standard D-2709. However, biodiesel which meets the D-6751 ASTM standard can still contain contaminants which tend to crystallize and/or form and drop out of solution as sediment. When such biodiesels are used at lower temperatures, the precipitates create problems by decreasing the fuel flow and by clogging fuel lines, filters, and other components of the engines burning the fuel.
Therefore, a primary objective of the present invention is the provision of a process for producing biodiesel which eliminates or minimizes the precipitation problems of this alternative fuel.
Another objective of the present invention is the provision of an improved biodiesel production process which utilizes cold filtration for removing impurities and contaminants from the biodiesel.
Still another objective of the present invention is the provision of a method for improving the quality of biodiesel by removing particulates therefrom prior to storage or transportation.
Yet another objective of the present invention is the provision of a process for cooling and filtering biodiesel for the removal of formed sediments.
Another objective of the present invention is the provision of an improved biodiesel production process which removes non-methyl esters and sterol glycosides from the biodiesel.
Still another objective of the present invention is a method of producing biodiesel by cooling the biodiesel with one or more heat exchangers which can be quickly and easily cleaned.
These and other objectives will become apparent from the following description of the invention.